1. Field of the Invention
The invention relates to an object detection apparatus provided in a moving body and adapted to output information regarding the position of an object related to the moving body, and the like, which is used in various controls including collision prediction safety control and moving body-to-moving body distance control.
2. Description of the Related Art
A known radar device is provided in a moving body (e.g., a motor vehicle) to detect an object (e.g., other motor vehicle) around the moving body. The radar device calculates, from various information it detects, the distance between the moving body and the detection target object, the speed of the detection target object relative to the moving body, the azimuth of the detection target object from the moving body. Such a radar device is used in, for example, an adaptive cruise control system for maintaining a constant distance between the moving body and the preceding moving body, a pre-crush safety system for minimizing the impact to the moving body upon collision, and so on.
One such radar device is described in Japanese Patent Application Publication No. 2000-206241 (JP-A-2000-206241). According to this radar device, multiple beams are first radiated and the waves reflected from an object (“reflection waves”) are then received, and the point from which each reflection wave has arrived (“reflection point”) is determined. Then, one or more reflection point groups each consisting of the reflection points estimated to belong to the same object are created, and output information is then created based on the ordination of the respective reflection points in each group. JP-A-2000-206241 describes setting a representative point to the reflection point closest to the subject moving body (subject motor vehicle) among the grouped reflection points and then outputting the set representative point.
In view of the fact that radar devices of this kind are often used to predict a collision between the subject moving body and an object (i.e., to determine the possibility of such a collision), a certain degree of rationality is acknowledged in setting the representative point to the reflection point closest to the subject motor vehicle among the reflection points belonging to the same object.
However, the radar device described in JP-A-2000-206241 does not provide any measure against a phenomenon that the representative point changes as a result of a change in the relation between the detection target object and the subject motor vehicle. When this phenomenon occurs, for example, the representative point on an object may move as if the object is approaching the subject moving body despite the fact that it is not approaching the subject moving body, and this may lead to an erroneous determination that the subject motor vehicle is likely to collide with the object and also lead to a temporary decrease in the accuracy of a process for detecting the moving speed of the object.